Online corrections — evidence‐based practice utilising electronic portal imaging to improve the accuracy of field placement for locally advanced prostate cancer

Abstract

AbstractGiven the onset of dose escalation and increased planning target volume (PTV) conformity, the requirement of accurate field placement has also increased. This study examines the role of online corrections (OC) to increase the accuracy of field placement. This study explores the role of radiation therapists in the process of achieving an online correction.Method Field placement data were collected on patients receiving radical radiotherapy to the prostate. Both intra‐ and inter field data was collected with OC being carried out within the confines of the Ballarat Austin Radiation Oncology Centre (BAROC) prostate Electronic Portal Imaging (EPI) policy.Results Statistical analysis of 740 portal images from 10 patients was carried out, illustrating that without OC field placement will fall at ± 7 mm on a daily basis. This evidence was further supported by a case study of computer dosimetry presenting the worst‐case possible impact upon a patient's total course of treatment if OC were not performed. Discussion The use of OC can prove to be of enormous benefit to both patient and practitioner. For centres with the available technology, it places the responsibility of field placement upon the radiation therapist. This responsibility, and the development of relevant protocols, in turn impacts on the education, training and empowerment of the radiation therapy group. These are issues of the utmost importance to centres considering the use of OC.Conclusions Without the use of OC there is a serious risk of underdosing both CTV and PTV. In this instance the CTV received only 60% of the prescribed dose, while the PTV received only 80% of the expected dose. OC are an important consideration for those looking to dose escalate.